The performance of classical spark ignition system and PJC ignition system developed by A.K. Oppenheim, has been tested in IC piston engine operating at full and partial load. Tests were conducted in the four stroke two cylinder engine. Differences in efficiency and emission for both ignition systems were tested for the power range from half load to full load. It was found that with the PJC system the engine operates more economically at the partial load and emission of hydrocarbons and CO was decreased at partial load. This was basically due to improvement of lean mixture combustion. However, the emission of NO was always higher for PJC than for conventional spark ignition.